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Automixable putty impression materialRelated Patent Categories: Synthetic Resins Or Natural Rubbers -- Part Of The Class 520 Series, Natural Rubber Compositions Having Nonreactive Materials (dnrm) Other Than: Carbon, Silicon Dioxide, Glass Titanium Dioxide, Water, Hydrocarbon, Halohydrocarbon, Ethylenically Unsaturated Reactant Admixed With A Preformed Reaction Product Derived From: (a) At Least One Polycarboxylic Acid, Ester, Or Anhydride; (b) At Least One Polyhydroxy Compound; And (c) At Least One Fatty Acid Glycerol Ester, Or A Fatty Acid Or Salt Derived From A Naturally Occurring Glyceride, Tall Oil, Or A Tall Oil Fatty Acid, Solid Polymer Derived From Silicon-containing Reactant, Mixed With Silicon-containing Reactant Or Polymer TherefromAutomixable putty impression material description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060293469, Automixable putty impression material. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The present invention relates to a multicomponent automixable putty impression material, its components, mixtures of the components and a method for obtaining impressions with the multicomponent automixable putty impression material. [0002] Impression materials are generally used for securing a precise representation of oral hard and soft tissue to support and enable subsequent preparation of crowns, bridges, dentures and other oral prostheses. Several impression taking techniques like monophase shaping (one material at one time), sandwich technique (two materials at one time) and putty/wash technique (two materials subsequently at two different times) are known to the skilled person. [0003] Generally, with this technique in a first step a putty material is used to obtain a supporting preimpression, which is subsequently in a second step refined by taking a second impression with a light body "wash" material. The kneadable putty material is cured as a preimpression material in the patients' mouth, trimmed after removing the preimpression from the mouth, and in a second subsequent step, is covered with a layer of a "wash" material and again cured in the patients' mouth in order to obtain a precise representation of oral hard and soft tissue. In the sandwich technique, this is done simultaneously during the pot life of the two materials, followed by simultaneously applying the two materials in the patients' mouth. [0004] The preimpression material (putty) is often employed in the form of a kneadable putty material. When performing a process for taking an impression, the dentist usually relies on the preimpression material having a noticeable resistance upon contact between preimpression material and dental material with the advantage that a higher back pressure is generated in the impression tray when the impression is made. Such a resistance is desirable, since the danger of overpressing the material in the tray is limited. Since overpressing usually results in direct contact between the impression tray and one or more surfaces of dental material, information is lost and the impression may be useless. [0005] One possibility for providing impression materials with a high resistance upon introduction into the oral cavity and onto the dental material the impression is to be taken from is to provide them with a high viscosity. Such high viscosities are, e.g., realized in putty preimpression materials. Such putty preimpression materials are generally provided as a 2K material with a base and a catalyst paste, where the base and the catalyst paste are taken from accordingly marked containers as lumps and the lumps are kneaded manually. [0006] In employing polyorganosiloxanes as putty dental impression materials, however, a number of difficulties have arisen. [0007] The above described dosage is usually effected with dosing spoons by means of which the kneadable material is removed from a container. This procedure is generally connected with a high expenditure of force. When the components are kneaded into a homogeneous compound, also a high expenditure of force is required. This procedure of dosing and mixing may involve a great number of errors, among which are wrong dosage and non-homogeneous mixing of the two components. Both factors can lead to insufficient cross-linking so that the precision of model making is no longer ensured. Additionally, kneading manually can introduce catalyst poisons into the material which may slow down or even partially prevent curing of the impression material, which can also be detrimental to the fidelity of the impression. [0008] Many 2K-Automix dental silicone putty materials so far show limitations with regard to the consistencies that can be mixed in the widespread available mixing devices. In the field of impression materials both, in the Pentamix.TM. and in the Garant-mixing systems, consistencies not higher than heavy body viscosities can be mixed due to the limitation of the forces which are necessary to push and mix the pastes. [0009] In order to overcome this problem, a number of so-called putty cartridge materials are known and commercially available. These materials are supposed to be processable with the above mentioned mixing systems and are offered as an alternative to kneadable putty materials. These materials have a light to heavy body consistency according to ISO 4823. Since these materials already exhibit a relatively high degree of cross-linking in the beginning of their pot life, generelly due to a rapid cross-linking reaction. As a consequence, the initial consistency of these materials is rapidly increased during the pot life so that their total pot life of the material, during which it can be successfully used is shortened. Upon exceeding of the pot life for a relatively short time or at unusually high ambient temperatures, the impression material may early form crosslinked, elastomeric domains or cure completely. Such an early curing or partial curing, however, may result in strained, distorted domains upon applying pressure un the material by the dentist so that the impressions are basically useless after removal from the oral cavity since the restoring forces of the elastomeric domains distort the impression. [0010] In US 2002/0147275 a multi component system for making impressions comprising at least two components A and B is suggested. Component A contains at least one compound having at least two alkenyl groups, at least one compound having at least one alkynyl group and/or at least one Si--OH structural unit and at least one organohydrogenpolysiloxane and component B contains at least one condensation catalyst and/or condensation cross-linking agent and at least one hydrosilylation catalyst. According to the specification, the material cures in two steps. The suggested system is, however, insofar disadvantageous, as the combination of Si--OH compounds and Si--H-compounds together in the base compound can lead to a decreased shelf life due to self condensation of the Si--OH-compounds even under mild basic or acetic conditions, and the reaction of Si--OH-Groups and Si--H-groups can result in the formation of hydrogen during storage or the setting reaction. [0011] In DE 101 16 223 it is suggested to prepare an automixable putty from two components A and B, wherein the mixing ratio of base and catalyst paste is 5:1 and the base paste has a Brookfield viscosity of 800 to 2000 Pas. The disclosed materials, however, usually require a modification of automixing systems. No two step condensation mechanism is described. [0012] It has thus been the object of the present invention to provide automixer-suitable impression materials based on addition crosslinkable polydimethylsiloxanes which can be mixed and dispensed by automixing systems. It has further been an object of the invention to provide automixer-suitable impression materials based on addition crosslinkable polydimethylsiloxanes which, due to a two-step reaction mechanism, undergo a transition in viscosity to form a kneadable putty material with increased viscosity in a first reaction step after mixing. [0013] The term "automixer-suitable impression material" in the context of the present invention relates to a multicomponent impression material which can be dispensed, for example, from a two-component disposable cartridge through a static mixer, e.g., of Mixpac (Keller EP 0 615 787 A1, EP 0 730 913 A1) or from tubular film bags in dual-chamber reusable cartridges through a dynamic mixer, e.g., in the "Mixstar" device of DMG-Muhlbauer (PCT/EP 98/01993 and PCT/EP 98/01858) or in the "Pentamix.TM." and "Pentamix.TM. 2" devices of 3M ESPE AG (EP-A-0 492 413 and EP-A-0 492 412). [0014] It has been a further object of the present invention to provide an impression material which avoids the drawbacks known from prior art impression materials as set forth above. It has further been an object of the present invention to provide a method for the preparation of impressions from objects from which impressions are to be made utilizing the impression materials as described below. In particular, the object has been to provide a multi-component impression material which can be simply and readily mixed and is automixer-suitable, suitable for making impressions and undergoes transition to an elastic solid state. [0015] It has now been found that a compositon containing a polyhydrogensiloxane, a vinyl terminated polydiorganosiloxane, a carbinol terminated or carboxyl terminated or amino terminated polydiorganosiloxane, a platinum catalyst and a condensation cure compound solve at least one of the above mentioned objects. [0016] The present invention therefor relates to a composition comprising [0017] a) at least one polydiorganosiloxane having at least two olefinically unsaturated groups as component (a), [0018] b) at least one organohydrogenpolysiloxane as component (b), [0019] c) at least one polydiorganosiloxane having at least one carbinol, carboxy or amino group as component (c), [0020] d) at least one condensation cure compound as component (d) and [0021] e) at least one addition cure precious metal catalyst as component (e). [0022] A composition according to the present invention is designed to provide a multi-step curing reaction, which enables the composition to be prepared by an automixing-system, to be applied to an object in a putty-like consistency and to cure by an addition reaction mechanism to secure an impression of the surface of the object. [0023] In order to be able to be cured by an addition reaction mechanism, the composition according to the present invention contains at least one polydiorganosiloxane having at least two olefinically unsaturated groups as component (a). Generally, according to the present invention all types of polydiorganosiloxanes having at least two olefinically unsaturated groups can be employed, as long as they are sufficiently reactive towards an organohydrogenpolysiloxane to yield crosslinked, cured preimpression materials which can serve the purpose of taking preimpressions of objects, preferably objects within the oral cavity of a human. Examples of polydiorganosiloxanes having at least two olefinically unsaturated groups include linear, branched or cyclic polydiorganosiloxanes with two or more vinyl groups. When a linear polydiorganosiloxane is used, such vinyl groups may generally be positioned anywhere along the polymer backbone or in one or more pendent groups. The vinyl groups may be positioned along the polymer backbone with even spacing or can be distributed randomly. While generally many types of polydiorganosiloxanes having two or more olefinically unsaturated groups will give good results when employed in the context of the present invention, the use of linear polydiorganosiloxanes with two to five olefinically unsaturated groups, preferably vinyl groups, preferably with two, three or four vinyl groups, is preferred. [0024] Diorganopolysiloxanes with terminal triorganosiloxy groups of which at least one of the three organic groups is a vinyl group are preferred as component (a). Preferred diorganosiloxanes of this structure are represented by the following formula I: in which the radicals R each independently from another represent a linear or branched alkyl or fluoroalkyl group with 1 to 8 C-atoms or a cycloalkyl or aryl group with 6 to 14 C-atoms or an alkenyl group with 2 to 12 C-atoms. [0025] The variable n is preferably chosen such that the viscosity lies between 4 and 200,000 mPas or between 6 and 100,000 mPas, preferably measured by a method as described in the text below. Preferred values for n are thus about 10 to about 2500 or about 20 to about 1500, depending on the types of substituents and the substitution pattern. [0026] The radical R is preferably chosen such that it is free from aliphatic multiple bonds. [0027] Preferably the radicals R can represent any non-substituted or substituted monovalent hydrocarbon group with 1 to 8 C-atoms, preferably 1 to 6 C-atoms. Generally, the radicals R can be equipped with all types of substituents that do not interfere with at least one of the remaining consituents of the composition and do not interfere with the curing reactions, e.g., fluorine substituents. The term "interfere" as used in the context of the present text relates to any influence of such a subsituent on at least one of the remaining consituents of the composition or the curing reactions, or both, which is detrimental to the properties of the hardened product. The term "detrimental" as used in the context of the present text relates to a change of properties of the precursors or the cured product that affects the usefulness of the precursors or the cured product related to the intended use of the precursors or the cured product in a negative manner. [0028] In another preferred embodiment of the present invention at least 50% of the radicals R represent methyl groups. Examples for other radicals R that can be present in the organopolysiloxanes according to formula I are ethyl, propyl, isopropyl, n-butyl, tert.butyl, the pentyl isomers, the hexyl isomers, vinyl, allyl, 2-propenyl, isopropenyl, 2- and 3-n-butenyl, the pentenyl isomers, the hexenyl isomers, fluorine substituted aliphatic radicals like 3,3,3-trifluoropropyl groups, cyclopentyl or cyclohexyl groups, cyclopentenyl or cyclohexenyl groups or aromatic or hereroaromatic groups like phenyl or substituted phenyl groups. Examples for such molecules are described in U.S. Pat. No. 4,035,453, the disclosure of which, especially the disclosure of the latter document regarding the above mentioned molecules, their chemical constitution and their preparation, is expressly regarded as being part of the disclosure of the present document and is included herein by reference. [0029] The preparation of molecules of the above mentioned formula I is generally known to the skilled person. The preparation of corresponding molecules can be achieved, e.g., according to standard procedures which are portrayed in W. Noll, "Chemie und Technologie der Silikone", Verlag Chemie Weinheim 2. edition 1964, pages 162-206 or J. Burghardt, Chemie und Technologie der Polysiloxane in "Silikone, Chemie und Technologie", Vulkan Verlag, Essen, 1989, pages 23-37. Continue reading about Automixable putty impression material... Full patent description for Automixable putty impression material Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Automixable putty impression material patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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